Fluid flow control device



Nov.`3, 1959 R. c. DU Bois 2,911,008

FLUID FLOW CONTROL DEVICE l Filed April 9. 1956 3 Sheets-Sheet 1 Nov. 3, 1959 R. c. Du BQls 2,911,008

FLUID FLOW CONTROL DEVICE Nov. 3, 1959 v R. c. DU Bols 2,911,008

f FLUID'FLow coN'rRoL nav-:CE

Filed April 9, 195s v s sheets-sheet s M0 M4( gar .4X4

United 4States teilt 2,911,008 FLUID FLOW CONTROL DEVICE Robert C. Du Bois, Fairfield, Conn., assignor to Manning, Maxwell 3L Moore, Incorporated, Stratford, Conn., a corporation of New Jersey Application April 9, 1956, Serial No. 576,945 16 Claims. (Cl. IS7-625.31)

This invention relates to fluid flow control means, and more especially to a device of adjustable type for restricting the ow of a fluid. While of more general utility the device of the present invention is herein illustrated by way of speciic example, but without limiting intent, in its application as a ilow restricting element 1n a pneumatic transmitting system. Such systems are commonly used, for example, in the remote control of or for indicating or recording variable conditions in an industrial processing apparatus or the like, and usually employ an elastic Huid, for instance air, as the signal transmitting medium. ln the design of such systems it has been found desirable, especially in systems where the measurement of temperature is involved, to provide an additional. mode of response which is proportional to the rate or first derivative with time of the variable condition. For this puipose it has been common to provide a delay in the feed-back action of the transmitter and usually with provision for adjustment of this delay so that it may be set to provide the best response under widely different conditions. One common way of providing such delay is by the use of a restriction in the feed-back line, which, acting in series with a capacitance, provides the time delay. Customarily this restriction has been-in the nature of a needle valve manually operated, and in order thata wider range of time delay may be provided for without causing instability in the transmitter itself, it is customary to provide a capacitance in parallel with the variable restriction, for instance a bellows enclosed Within a suitable chamber.

Although it is customary to employ a needle valve as the restriction in the feed-back line as above noted, such a valve is not wholly satisfactory, not only because of difficulties involved in the design of a valve of this type intended to provide extreme attenuation of the fluid flow but because the inherent design of a needle valve is such that it easily clogs with dust or other particles carried by the fluid stream. It has also been proposed to employ a passage of capillary type and of variable eifective length as the flow restricting means. However, this arrangement isV subject to certain limitations (in embodiments of practical size) withrespect to the range and degree of attenuation of ilow provided.

e An o bject of the present invention is to provide a restriction device of adjustable type useful, for example, in such a transmission system as above referred to, and also, it is contemplated, in other situations where a variable restriction is required, particularly where great range and/or high attenuation of the rate of Huid ilow is involved, and such as will not readily be clogged by the accumulation of dust or other particles carried by the iluidstream and which if it does become clogged may readily be cleaned. A further object is to provide an adjustable restriction device which may =be so designed that in response to a linear adjustment of the actuating element either a linear or a higher order of variation in the restriction may be obtained. A further object is to ICC e provide a novel restriction device which may, if desired, be employed to advantage as an element of a pressure dividing apparatus of that type wherein the ow of iluid from a sigle inlet port to either of two outlet ports or vice versa is controlled by a movable part having at least two flow restricting passages, each of which embodies the principle of the present invention. A further object is to provide an adjustable restriction device of a type which, while ordinarily actuated manually, readily lends itself to automatic adjustment, for example by mechanical or electrical means. A further object of the invention is to provide simple means'providing for the simultaneous adjustment of a plurality of variable restrictions. A further object is to provide flow control apparatus designed to be installed in a Huid passageway running between a positive feed-back chamber, a negative feed-back chamber and the output control signal passage of an elastic fluid pressure controller such that two variable restrictions may be simultaneously adjusted. Other and further objects and advantages of the invention Will be pointed out in the following more detailed description and by reference to the accompanying drawings, wherein Fig. l is a vertical diametrical section through a simple embodiment of the restriction device of the present invention and showing a capacitor in the form of a bellows arranged in parallel relation with the restriction device proper;

Fig. 2 is a view looking upwardly from the plane of the line 2 2 of Fig. l, showing the underside of the movable element of the restriction device of Fig. l;

Fig. 3 is a fragmentary vertical section, to larger scale, showing the movable element of the restriction device and the sealing ring which cooperates therewith;

Fig. 4 is a vertical section similar to Fig. l, but showing the principle of the present invention as incorporated in a pressure divider of simple type;

Fig. 5 is a View looking up from the plane of the line 5 5 of Fig. 4, showing the underside of the movable element of the device of Fig. 4;

Fig. 6 isla view similar to Fig. 5, but showing a pressure divider of another type embodying the principle of the present invention;

Fig. 7 is a view similar to Fig. 6, but illustrating a different arrangement of the flow restricting grooves;

Fig. 8 is a diametrical section illustrating the principle i of the present invention as embodied in a flow restricting device wherein the grooves are in the peripheral surface of a rotatable cylinder;

Fig. 9 is a view generally similar to Fig. 8, but showing a pressure dividereembodying the principle of the present invention, wherein the ow restricting grooves are formed on a cylindrical surface;

Fig. l() is a fragmentary radial section, to larger scale, showing an arrangement generally similar to that of Fig. 1, but with provision for greatly increasing the range of flow restriction;

Fig. 1l is a bottom view of the movable element of the device of Fig. l0;

Fig. 12 is a fragmentary section substantially on the line 12412 of Fig. l0;

Fig. 13 is a diagrammatic fragmentary vertical section which, in simple form, illustrates the underlying principle of the invention;

Fig'. 14 is a section on the line 14-14 of Fig. 13;

Fig. 15 is a view generally similar to Fig. 13, illustrating a more practical embodiment of the basic principle;

Fig. 16 `is a diagram, showing in plan, a groove which tapers in width;

Fig. 17 is a diagram, showing in plan, a groove of uniform width; and

Fig. 18 is a view, generally similar to Fig. 15, but showing a groove designed to provide a non-linear flow attenuation.

Merely as an illustrative instance of theV use of such a restrictive device as that hereinV disclosed, reference may be had to the patent to Ziegler 2,512,561, lune 20, 1950,V which concerns, in particular, apparatus which responds to temperature variations and wherein a restrictive device such as an ordinary needle valve 22 has' associated therewith a stabilizing capacitance 2.0.

The conventional needle valve, when employed as a restriction in a' system of the kind above referred to is inadequate because its basic design places the needle or flow-restricting element at the center of the stream, so that the stream itself is caused to take the form of an annular shell whose radial thickness is substantially less than the radius of a circular passage having the same volumetric capacity. ln accordance with the present invention the desired restriction is accomplished by means such that the flow takes place in the form of a solid stream at all capacities,-so that danger of clogging is minimized. Moreover, in accordance with the present invention, thorough cleaning of the restriction passage is very easy as compared with the attempted cleaning of a clogged needle valve.

Referring to Fig. 13, the principle of the invention is diagrammatically illustrated wherein the numeral 400 represents a rigid plate or base member having a finished and plain horizontal upper surface 401 onl which there rests a block 402 having a smooth lower surface, making leak tight contact with the surface 401. The block 401 will be accurately guided to move back and forth in a rectilinear path in therdirection of the arrow A.

The block 402 has an elongate chamber 404 in its lower side, it beingY here assumed that this chamber is rectangular in transverse section. In the roof 405 of this chamber there is an elongate groove 406 (also assumed to be of rectangular transverse section and of less width than the chamber 404), the roof of the groove sloping so that the height of the groove progressively tapers from its left-hand end to its right-hand end. The numeral 407 designates a barrier wall or dam` whose lower part seats with a sliding tit in a slot in the base member 400, a resilient element 403 being arranged to urge` the barrier wall upwardly to cause its flat edge surface 409 to make leak-tight contact with the ungrooved portion of the roof 40S of the chamber'40`4. The barrier wall 407 thus normally cuts oit communication between the left-hand portion of the chamber 404 and the space y410 to the right of the barrier wall. A lluid ow passage 411leads down through the base member from the space 410 and another uid flow passage 412 extends through the block intothe chamber 4404;

lf the block 402 be moved slightly to the left ofthe position as shown in' Fig. 13, no liuid can pass from the chamber 404 into the space 410 to the right of the barrier wall 407. k However, when the block is' positioned as shown in Fig. 13, a portion of the groove 406 extends across the upper surface 409 of the barrier vwall or dam and beyond the right-hand face of said wall or darn., Y As soon as any portionV of the groove passes the plane of the right-hand face of the barrier wall the upper surface 4109 and the wall of the groove overlying said surface cooperate to define an oriiice O (Fig. 14) through which fluid may ow from theschamb'er 404 into the space 410. The effective area of this orifice is in the plane of the righthand surface of the barrier wall or dam 407, and will vary as the block is moved and so causes various portions of the groove to register with the upper surface of the barrier wall. s A

Thusit is manifest that no fluid can pass from chambei 404 to space 410 except asA it flows across the upper edge 409 of the barrier wall or dam 407, arid since the barrier Wall or dam will usually separate the space 404 in which a relatively high pressure is maintained from the space 410 in which a lower pressure subsiste, it is convenient to consider the barrier wall 407 as a dam having the surface 409 as its crest. As shown in Fig. 13, this dam is a simple rectilineal wall standing transversely of the length of the chamber 404 and transversely of the length of the groove 406.

However, it may be more desirable to make this dam in the form of a short tube, here shown as circular, whose axis is perpendicular to the plane of the surface 401 and whose central bore will then function like the space 410 above described. Conveniently said central bore will be in axial alignment with the upper part at least of the passage 411 or its equivalent. Such an arrangement is diagramatically shown in Fig. 15, wherein the rigid seal ring 413 constitutes this annular dam, its flat, annular upper surface 409:1 constituting the crest of the dam while the space 410:1 inside this seal ring corresponds in function to the space 410 above described. In this arrangement this space 410 is axially aligned with the passage 411e in the base' member 400, the lower edge of the seal ring 413 seating' upon a conventionall O-ring 414 resting on the bottom of a cavity extending downwardly from the surface 401 of the base 400. This O-ring acts resiliently to urge the seal ring 413 upwardly to cause its upper edge 409a to make leak-tight contact with the roof of the fluid receiving chamber 404, and also to provide a leak-tight seal between the ring 413 and the base member.

By sliding the member 402 toy the left or right, the efectiverarea of the orice where the groove 40'6 registe'rs with the surface 40911 of the' seal ring will vary by reason of the slope of the upper wall of the groove, and thus'a varied restriction of the flow of the fluid is readily attainable by such adjustment of the part 402. Of course, when thedam is tubular, and the outlet chamberjllttia is constituted by its central bore, there are really two orifices located at opposite sides respectively of the bore. Obviously, the rate of variation may be changedby providing a diiferent slope for the upper wall or roof of the groove.

In Fig'. 16, the darn is indicated at 413 as a circular annulus while the groove 406m is to be understood as of isosceles triangular form in plan but with its converging walls vertical and with its top wall horizontal, so that the variation inl transverse section is due entirely tothe tapering width of the groove.

In Fig. 17 the dam is a short tube, square in transv'erse section, indicated by the numeral 413n and is what here for convenience is called a square annulus, that is to say in plan it is a hollow square, while the groove4 40671 is of uniform width having parallel, vertical Aside walls, but with the understanding that the Vtop wall or roof of the groove slopes down from its lefthand end toward its right-hand end. v

In' Fig. 18 the arrangement is generally similar to that illustrated in Fig. 14 except that the roof 406b of thev groove 406 is of arcuate contour, thus providing an orifice whose area varies progressively in accordance with a' non-linear function. Obviously, this form of groove may be used in any of the various embodiments of the invention herein described. For convenience in description the termsl annulus and annular are herein employed as broadly descriptive of a tubular part, usually axially short as compared with its external diameter, and whether the transverse section of this part be circular or, for example, rectangular. It is obvious that' when, during motion of the block 402 to the right, theV righthand' endl of the groove or channel passes the right-hand portion of the upper edge of the ring 4 13, there will be 'two spaced sections' of the groove at which fluid passes into* the bore in the ring 4lf3'and that1 the effective area of the delivery orifice will be the sum of these two sections.

2,91 LOS more practical embodiment of the invention is illustrated, for example, in Figs. 1, 2 and 3. The device as shown in Figs. 1, 2 and 3 is circular in contour, com` prising the disk-like normally stationary rigid Vbase 50 and the rotatable knob 52 held in assembled relation to the base by the shoulder screw S which constitutes a stub shaft on which the knobV turns. Rotation of the knob 52, relatively to the 4base, results in variation of the iiow restriction. The upper surface of the base 50 near its outer margin; is provided with a groove in which is seated a conventional O-ring 53 of resilient material providing a leak-tight packing between the upper surface of the base 50 and the undersurface of the knob 52. This O-ring 53 is concentric with the shoulder screw or shaft S by means of which the knob 52 is rotatably secured to the base 50, A second O-ring 54 of smaller diameter than the ring 53 is seated in a groove concentric with the screw S and which also forms a leak-tight seal with the undersurface of the knob 52. The rings 53 and 54 project above the upper surface of the base and provide between them a shallow annular chamber 55. A passage 56 in the base leads into the chamber 55, the passage 56, when the device is used as an element of a pneumatic transmitter system such as above described being connected by a suitable conduit (not shown) -to an air relay. At a point, here shown (but not necessarily so) as diametrically opposite to the passage 56, the base provided with an outlet or delivery passage 57 which, when the device is employed as above suggested, will be connected by a suitable conduit (not shown) to the feed-back of the system. The delivery passage 57 is provided with an upward extension 57a (Figs. 1 to 3) whose upper end opens into a circular cavity 5S (Fig. 3) coaxial with the upward extension 57a of passage 57 and within which there is arranged a resilient O-ring 59. In this cavity or chamber 58 and on the O-ring rests a tubular dam or sealing ring 60, movable relatively to the base 50, and having an accurately finished and flat upper surface which contacts the finished under surface 61 of the knob 52 with resilient pressure, the contact between these surfaces being suiiciently accurate so that normally pressure uid from the chamber 55 cannot pass between the upper surface of the ring 60 and the undersurface of the knob 52 into the space at the center of the sealing ring.

As more particularly illustrated in Fig. 2, a groove 62 is formed in the underside of the knob 52, this groove as here illustrated being triangular in vertical section (Fig. 3) and tapering in height and in base width from its wide end 62a (Fig. 2) to its narrow end 62b, the groove being so arranged that its apex edge is a circle coaxial with the shaft S. Desirably the wider end 62a of this groove opens into a slot 63 of transverse dimen-l sions substantially exceeding the width of the Widest part of the groove. 1`

The groove is freely open tothe chamber r55 except for such portions of the groove as extend across the upper edge of the seal ring or dam 6 0. Thus it is always possible for pressure fluid to enter the groove from the chamber 55, and so long as .any portion of the groove extends transversely acrossone edge of the seal ring, pressure uid will flow along that part of the groove which overlies the upper edge or crest of the seal ring or dam and will enter the central bore in the seal ring and thus move down through the passage 57a and into the outlet passage 57. It may be noted that at the place or places Where the groove crosses the seal ring or dam the upper surface of the seal ring forms-the crest of the dam and the eiective floor of the groove so that at this point or these points the transverse sectional area of the groove is definitely fixed. This portion of the groove constitutes a short delivery channel of fixed length (equal to the radial thickness of the seal 6 nel'thus constitutes the effective restriction, the transverse area of the bore in the seal ring being at least as great as that of the delivery section of the channel so that any iiuid emerging from the channel into the bore in the seal ringis free to escape. By turning the knob 52 varying transverse sections of the groove are brought to coincide with the upper surface of the seal ring 60 so that the degree of restriction will be varied accordingly. When the slot 63 is brought into coincidence with the :bore of the seal ring, then a maximum and unrestricted flow between the chamber 55 and the outlet passage 57a is provided.

As illustrated in Fig. 1, a casing 64 is secured to the base 50 and a branch passage 65 leads into the interior of this casing from the inlet passage 56. Within this casing there is arranged a bellows 65a having its upper end secured to the base 50, and a branch passage 66 leads into this bellows from the passage 57. Such a bellows, within a closed housing, is useful as a capacitance in parallel relation with the restriction device of the present invention, but forms no part of the present invention.

The arrangement illustrated in Figs. 4 and 5 constitutes a pressure divider in which restriction means such as above described is employed. The device shown in these views is circular in contour, comprising the rigid base member 50a, generally similar to the base 50 of the device previously described, except that it has two inlet passages 56a and 56h. This hase also has `the single outlet passage 57 and the inner and outer concentric O- Iings 53 and 54deining between them the shallow chamber 55 between the upper surface of the base and the undersurface of the rotary knob 52a which is rotatably secured to the base by the shoulder screw S or stub shaft. The passages 56a and 56b have upward extensions which open into chambers like the chambers 58 above described, in each of which there is seated an O-ring. On these O-rings rest rigid sealing rings 60u and 61b respectively, here shown (Fig. 4) as integrally joined, the upper surfaces of these rings making leak-tight contact with the flat undersurface of the knob 52a. The undersurface of the knob 52a is provided (Fig. 5.) with two grooves 62 and 62a respectively, similar in type to the groove 62 above described, and with their apex edges forming circular arcsV coaxial with the shaft S. In this arrangement the taper of the grooves is in opposite directions. One of these grooves is arranged to register with the space within the O-ring 60a, while the other groove is arranged to register with the space within the O-ring 60ib. It will ,be manifest that if, for example, fluid at different pressures be supplied to the inlets 56a and 56b, the pressure which enters the chamber 55 will vary according to the sum of the areas of the two `grooves 62 and 62a, which -at any instant may register with the inner edges of the seal rings 66a and 66b respectively. By proper shaping of the restriction grooves it is possible to maintain a constant restriction between the two ports formedKV by the seal rings.y By rotating the knob it is possible to change the ratio of the restriction between the outlet 57 andthe inlet ports defined by the seal rings 60a and 60b. Obviously, the port 57 may be the inlet and the ports 56 and 56b the outlet ports, if desired.

Fig. 6 illustrates another modification wherein the base (not shown) is provided, as indicated in broken lines, with inlet passages 56x and 569 at diametrically opposite sides of the shaft S and also with the outlet passage 57. The knob 521) is provided at its underside with grooves 62x and 62y, each similar to the groove 62 above described, and of substantially the same diameter and arranged concentrically with the shaft and tapering in the same direction. Each of these grooves is arranged to cooperate with a seal ring at the upper end of the inlet port 56x and 56y respectively, thus providing an arrangement diieringin details of construction from that of 2,91 noos- Figs.,4,and and having Vsomewhat different capabilities, insofar as ,function isconcerned. g g

Fig. v7 illustrates an arrangement Wherebytwo independent restriction grooves maybe combined in asiigle Unif- In this device. ,the base' (ily shown). iS. PEF/ids@- eS-,iidcated by, the breken lines, .with WQ. inlet passai-1.6.8 564.21m 5:61? likefhat .Ofiss 5V and @bei it is also Pr@- vided Withtwo independent outlet passages 57 and 571?. rlfhe `underside of the rotatableknob is provided two concentric grooves 62 and 6211, both tapering in the same direction and so arranged that one coincides with a sealing ring at they upper endof the inlet passage 56a, while the other cooperates `with a sealing ring at the upper endof the passage 5611'. A third (ji-ring 53a intervenes between the" grooves' 62 and 62a, thus providing independent chambers `from which 4the outlet passages 57 and' 57a lead. l

Grooves'- such as above described may readily be formed by placing the knob in a4 lathe chuck and mounting a properly shaped tool inthe `tool rest of the lathe, and, after contacting the tip of the tool with the face of the knob, moving lthe tool toward the knob by the feed screw of the lathe while turning the knob through the desired arc. Obviously, by the use of properly designed cams the cutting tool might be so controlled as to form a groove of almost `any desired contour and with a cross-section varying, if desired, in accordance with a non-linear function.

Since by removing the screw S the knob maybe completely separated from the base, thus exposing the entire length of the groove, it is very easy to clean the groove if it become clogged with dirt during use.

Fig. 8 illustrates a pressure divider embodying the principle of the presen-t invention, but in which the restriction groove is formed on the peripheral surface of a Vcylindrical block. In this device the stationary member or base takes the form of a cylinder 7) having an internal chamber '7i within which is arranged the cylindrical plug or block 72. At its left end, as shown in Fig. 8, the plug is provided with a shaft 73 by means of which it may be turned relatively to the casing 79. At its opposite end the plug bears against a removable ring 74 secured to the casing and which holds the plugin assembled relation with the casing. Near the opposite ends of the chamber 7l the inner wall of thela'tter' is provided with grooves in which the O-rings 75 and "76 are seated. Substantially midway between these (ft-rings the casing is provided with an outlet port 77, while at its diametrically opposite side it is provided with the axially spaced inlet ports 78 and 79. The effective inner end of each of these inlet ports is'dened by a seal ring or dam 8() and 81 respectively, which may be integrally joined as shown in Fig. 8, having inner surfaces which are cylindrically curved to make leak-tight Contact with the finished peripheral surface of the plugl 72. As shown v in Fig. 8, the plug is provided with two peripheralrly extending grooves 82 and g3, here shown as tapering from one end toward the other, the tapering ot' the respective grooves being in opposite directions circumferentially of the plug. These grooves are arranged to register with the interiors of the seal rings y89 and S1 respectively. Rotation of the plug 72 in one orthe other direction changes the effective areas of the sections of the two grooves where the grooves register with ythe respective seal rings and thus varies the ratio of the pressures provided at the inlets 77 and 78 and so determines the pressure lat the outlet port 77, in the same Way as the device illustrated inFigs. 5 and 6.

The arrangement shown in Fig. 9 has for its purpose the provision of a greater range of attenuation than is provided in apparatus such as illustrated in Fig. 1 for example, but without making the apparatus of undue diameter. The arrangement of Fig. 9 is of the same general type as that shown in Fig. 8) comprising the casing 70a having'- the cylindrical internal chamber 71,

8 in, which` there is", arranged a rotatable cylindrical plug 72a having a stem 73a by means ofl which itv may yb e turned... VNear Yits opposite epds the ychamber 71 is provided with( Q-ringsnandn76 seated in suitable grooves in theuchaniber wall, anl the sealed-up` portion of chamber 71 lbetween lthese rings communicates 4with the outlet` passagem7'7,A In this arrangement there is a single inlet passage 78g Whose `eiective inner end is deiined bya rigid seal kring or damtila set into a recess coaxial with the passage 7821, whose innersur'face is concentrically curved to male leakight Contact with the outer surface of thelplg 72u.y single restriction groove 35 is formed in the outer surface of this plug 72a, but in Y this Vinstance the groove makes several complete turns about the plug. Y Thus the total length of the groove may be much greater 'than that of the groove 62 of Fig'. 8', thus permitting a greater'rang'e the restriction or permitting a more gradual attenuation. This groove 85 is arranged as a helix of predetermined pitch, and in order that the groove lmay at all times yregister with the interior of the statioriaryseal ring Sla, the shaft 73d is provided with a screw` thread `86 of` the same pitch as thehelicalgrove 85, this screw thread engaging a threaded here s? it fieljcasing 'ma rims as the Shao 73a is' turned v,the plug 172ai`sV moved axially (While rotating) just'ysufciently to keep the groove 85 always in register with the opening in the seal ring Sla.

The arrangement illustrated in Figs. l0, ll and l2 is amodication of that shown in Figs. l, 2 and 3, but so arrarig'ed as to permit the employment of a guide groove of more than 360 eitent. vIn this arrangement the 9o and' 'the rotatable knob $1 are held in assembled relatiijiriV means. of the shoulder screw or stub shaft S. The base 90 is provided in its upper surface with lconceh'tri; grooves.which receive the O-rings 92 and 93 defining between them the air-tig. t chamber 9131. In the undersur'fface of the knob 91 there is provided a restrictionl groove' 9S (Fig. ll) of the same general type as that above suggested, except that in this instance this restriction groove' is in the form of a spiral here shown aslof tvvoco'mpleteturris, the groove progressively tapering` in transverse dimensions from its inner to its outer en'd.

A sealing C'le'nt or darn 916 engages the undersuriace of the' knob w91' withaleak-tight contact. This sealing' element as" here illustrated is' cup-like in construction, having a recess its bottoni which receives a coiled compression spring' 9S which urges the ring upwardly toward the knob 91. The undersurface of the knob 91 is provided with a ldownvva'rdly directed rigid rib 99 of the same type of spiral curvature as the groove and which is Vso arran'ge'da's' always to be at the same distance 'radially fromv the grove. The verticalfaces of this rib are `iinishfed to mak'smoothsliding Contact with the lateral surfaces of the seal element 96. The lower part of this seal .element'is arranged within a radial lslot @7 (Fig. l0)` in lthe base Q Gso that the sealing element may move in a radialdirection.Y the knob 91 is turned, the rib 9S, acting `asian cam, moves the sealing element 96 in or out, thus keeping theV space 19S within the upper part of the sealing" element always'in registry with the groove 9S. The sealing element is provided with a port T in its wall, this port is connected by a flexible tube 192 (Fig. l2) with yan outlet port `1Q?,l inthe base 9b?. An inlet port 194 l0)` in thehbase admits iiuid pressure into the chamber l94, and since some portion of the groove 95 always opens intothis chamber, the uid pressure follows along theV groove to the sealing element where the sum of those sections of 'theg'roove which are in registry with the upper edge of thegsea'ling element detines the effec-- tive restrietioi atv any given setting of the knob 91. This arrangementv permits the employment 0f a restriction groove of very substantial length Without unduly increasingV- the" diameter of the apparatus as a Whole.

l`nthe description and vdrawings one of the parts has been described as movable relatively to the other, but in general it is to be understood that it is immaterial which of said parts is the movable part (in fact, both may be movable if desired). Moreover, it is contemplated that the groove and dam may be reversely arranged as respects the part with which they are associated, and that the device is operative to control the flow of other fluids than air. It will further be understood thatby change in dimensions the principle of the invention may be embodied in apparatus for controlling the flow of much greater volume of fluid than is to be expected in devices of the specific utility above suggested.

While various utilities of the restriction element of the present invention have herein been suggested and illustrated, it is contemplated that other arrangements and variations in the use of this restriction device will occur to those skilled in the art, and it is to be understod that any and all such modications, rearrangements and utilities of the invention as fall within the terms of the appended claims are to be considered as being within the scope and eld of the invention.

I claim:

l. A flow restriction device comprising a normallystationary member and a relatively movable member, said members having spaced opposed surfaces which are always the same distance apart, the surface of the movable member being a finished surface, means which define the lateral wall of a fluid-receiving chamber whose other walls are constituted by said opposed surfaces of said members, one of said members having therein a passage providing communication between said chamber and the exterior of the device, the stationary member having a iiuid passage the inner end of which opens at the aforesaid surface of said stationary member, said latter passage extending -to the exterior of the stationary member, the latter member carrying a tubular darn which projects from its aforesaid surface and extends across the fluidreceiving chamber and has a finished end face which always contacts the opposed finished surface of the movable member, the interior of said dam always communieating with the fluid passage in the stationary member, the dam being operative, when the stationary and movable members are in a certain relative position of adjustment, to constitute a barrier to prevent fluid ow between the Huid-receiving chamber and the inner end of said iiuid passage in the stationary member, the movable member having in its finished surface, an elongate groove which increases progressively in transverse section from one end toward the other, said groove being of such configuration and so located that as the result of adjustment of the movable member relatively to the stationary member, any selected portion of the length of the groove may be made'to register with`th'e end face of the darn thereby providing at least one channel of fixed length connecting the fluid-receiving chamber and the inner end of said uid passage in the stationary member, the wall of the tubular dam being of such a thickness, in the direction-of fluid ow, that the length of said channel does not substantially exceed the diameter of said passage in they stationary member.

2. A flow restriction device comprising a normally stationary member and a relatively movable member, said members having spaced opposed surfaces which are always the same distance apart, resilient means interposed between said surfaces making leak-tight contact therewith and defining the lateral wall of a fluid-receiving chamber whose other walls are constituted by the aforesaid surfaces of the fixed and movable members respectively, the normally stationary member having therein at least two fluid passages, one end of each of said passages being Iat said surface of the stationary member, the passages extending to the outside of the stationary member, a rigid tubular dam whose interior always communicates with one of said fluid passages, said dam projecting from said surface of the fixed member across the duid-receiving chamber, the dam having a finished end face which always contacts said opposed surface of the movable member and thereby, in certain relative positions of the stationary and movable members, prevents Huid flow between the Huid-receiving chamber and the iluid passage which communicates with the interior of the tubular dam, the movable member having, in its aforesaid surface, an elongate groove which increases progressively in transverse section from one end toward the other, the groove being of such longitudinal coniigurationV and so located that as the result of adjustment of the movable member,A relatively to the 'fixed member, a selected portion of the: length of the groove may be made to register with the: end face of the tubular dam, thereby providing two short; delivery channels each of a ixed length equal to the-y thickness of the wall of the dam but which varies in Width in accordance with the position of the movable: member relatively to the fixed member.

3. A liow restriction device according to claim l, wherein the inner end portion of the pass-age in the stationary; member is diametrically enlarged to form a dam-receiv ing cavity, and the dam is slidably arranged within said". cavity, resilient means urging the dam in an axial direc tion bodily toward the movable member thereby to maintain its end face in leak-tight contact with the opposed? finished surface of the movable member, the `major por tion of the length of said groovev always being in free: communication with said fluid-receiving chamber but: being of such longitudinal configuration and so located that, as the result of adjustment of the movable member relatively to the fixed member, different selected portions of the length of the groove register with the crest of the dam thereby providing at least one delivery channel of a fixed length equal to the thickness. of the wall of the tubular dam but varying in width in accordance with the position of the movable member relatively to the fixed member, the thickness of the wall of the dam, in the direction of fluid flow, being small as compared with the length of said groove.

4. A ow restriction device according to claim l, wherein the finished outer end surface of the dam is of such contour that'when said members occupy certain relative positions of adjustment, two delivery channels of different transverse widths, respectively, result.

5. A ow restriction device according to claim l, wherein the dam is a short cylinder having an axial bore which v is coaxial with the inner end portion of said fiuid passage in the stationary member, the end surface of the dam beving 'flat and annular.

6. A ow restriction device according to claim l, having a dam-receiving cavity in the fixedmember which is circular in transverse section and wherein the dam is a cylindrical member slidably fitting within said chamber, its outer, circular end surface constituting its crest, and having a resilient ring within the dam-receiving cavity upon vwhich the cylindrical dam rests and which maintains the crest of the dam in leak-tight contact with the opposite surface of the movable member.

7. A ow restriction device according to claim 1 wherein the relatively movable members have substantially at, parallel opposed surfaces, means connecting said members for relative rotational motion about an axis perpendicular to said surfaces, and wherein the means which provides the lateral wall of the fluid-receiving chamber comprises concentric O-rings whereby the uidreceiving chamber is annular and coaxial with the axis of rotation.

8. A flow restriction device according to claim 5, wherein the groove in the rotatable member is triangular in transverse section and of a longitudinal configuration such that the apex of the triangle is concentric with the axis of rotation of the movable member.

9. A ow restriction device. comprising a normally fixed base, a knob, and pivot means holding the knob and base in assembled relation with provision wherebyfb the knob may berotatably adjusted relatively to the base, the base having a horizontal upper surface and the knob having a horizontal lower surface, concentric -rings interposed between said surfaces and holding said surfaces spaced apart, the annular space between the O-rings constituting a chamber for the reception of pressure huid, the base having passages through which pressure huid may be admitted to said chamber and discharged therefrom, respectively, one of said passages leading downwardly from a recess in the base which opens ,at the upper surface of the base, an O-ring seated in said recess and a rigid sealing annulus, which constitutes a darn, resting on the G-ring, the sealing annulus extending completely across the chamber and having a smooth end surface which contacts said lower surface of the knob, leal?.- tight, the knob having in its lower surface a groove of progressively varying transverse section, said groove being coaxial with the pivot means and of such radius that by adjust-ably rotating the knob, any selected portion of the length of the groove may be arranged to extend transversely across said end surface of the annulus, that minor portion of the length of the groove, which at any time registers with the end surface of the sealing annulus, coacting with the latter to define at least one Jflow-.restricting channel, the major portion of the length of the groove normally communicating with the huid-receiving charnber.

10. A flow restriction device according to claim 1, wherein one of said movable parts is cylindrical and turns leak-tight in axially spaced bearings in the` other of said parts, one of said parts having a circumferentially extending recess located intermediate said bearings and which constitutes the huid receiving chamber, the groove extending circumferentially of the other of said parts', the dam being carried by that part which has the circunferential recess and extending across the recess withl its crest making leak-tight contact with the opposed cylindrical surface ofthe other of said parts.

11. A flow restriction device according toV claim l, wherein one of said movable parts is a cylindrical plug turning leali-tight in axially spaced bearings formed' in the other of said parts, the latter part having a circumferentially extending internal recess located between said bearings and constituting the uid receiving chamber, the groove being in the peripheral surface of the plug, the dam' being a cylinder having an axial bore which is radial with respect to the axis of the plug and which is carried by that part in which the recess is formed and extending radially inward across the recess with its crest making leak-tight contact with the peripheral surface of the plug.

12. A ow restriction device according to claim 1, wherein the movable member has therein independent grooves, each of varying transverse section, each Vof said grooves being in constant free communication, throughout the major portion of its length, with said chamber,

a plurality or" dams, in number equalling the number of grooves, each dam being mounted in the xed member and extending transversely across said huid-'receiving chamber, and having an end surface which makes leaktight contact with the movable member, each dam being so constructed and arranged as normally to cut off a corresponding space from the chamber proper, the spaces so cut oi being always in communication with'rcorresponding independent flow passages in said iixed member, theseveral grooves being ,so located that relative movement of said members will bring successive portions of cach respective groove into registry with said end surface of a corresponding one of said dams, therebyto define at least onevorice through which fluid may ow between said chamber and the corresponding passage, and wherein the width of the crest of each respective dam, in the direction of uid flow, does not substantially exceed the diameter lof the corresponding flowppassage, eachV dam havinghan vannular-wall separating `the lspace withinrit from the fluid-receiving chamberproper, the space within each annularwall always being incornmunication with a corresponding one of said independent `passages in the stationary member, the several groovesbeing so located that relative vrotation of said members will cause successive portions of the respective grooves to register with the crests of the corresponding dams. A Y r p I 13. A device according to claim` 1, having a plurality of. annular dams mounted in the xed member andrhaving their end faces in leak-tight Contact with the movable member, the xed member having independent passages communicating with the interiors of the respective dams,

the movable member having a pluralityvof elongate grooves each of varying transverse triangular section,

and each groove being in constant communication with( said chamber, said grooves being so arranged that by rotation of the rotatable member successive portions of each respective groove may be caused to extend transversely across the crest of a corresponding one of said dams.

, 14. A pressure divider according to claim 13, wherein the several grooves are arcuate and progressively taper in transverse area from one end toward the other, the taper of adjacent grooves beingin opposite directions.

15. A pressure divider according to claim 13, wherein the several grooves are arcuate and coaxial with the movable member and progressively taper invtransverse area from one end toward the other,. the taper of adjacent grooves b'eingin the same direction.

16. A pressure divider according to claim 13, wherein the xed member is a part having therein a cylindrical cavity and the movable part is a cylindrical plug disposed within said cavity, the wall of the cavity having axially spaced bearing surfaces within which the plug turns, the wall of the cavity having therein a recess intermediate said bearing portions which constitutes the huid receiving chamber, the fixed member having a plurality of passages, the tubular dams being seated in recesses in the fixed member, the end faces of the dams being so curved as to make leak-tight contact with the periphery of the plug, each groove being disposed in the diametrical plane through the axis of one of the dams, respectively.

References Cited in the le of this patent UNITED STATES PATENTS 1,015,297 Chatillon Jan. 23, 1912 1,076,281 Gray Oct. 21, 1913 1,314,987 Smith Sept. 2, 1919 1,527,927 Schroder Feb. 24, 1925v 1,983,213 Brady etal Dec.v 4, 1934 2,012,004 Hall et al. Aug. 20, 1935Y 2,236,084 Brown Mar. 25, 1941 2,290,783 Turpin July 21 1942 2,323,115 Bryant `lune 29, 1943 2,384,078 Curtis Sept. 4, 1945. 2,447,920 Terry Aug. 24, 1948 2,572,950 Rider Oct. 30, 1951 2,631,811y Malloy Mar. 17, 195,3 2,633,325 whiuock Mar. 31, 1,953 2,766,771 Wenzel Oct. 16, 1956 FOREIGN PATENTS 21,477 Great Britain Aug. 1, 1912 628,170 France June 21, 1927 560,262 Great Britain Mar. 28, 1944 

